A Chinese immigrant who was beaten and robbed as rioting broke out in Los Angeles last year testified Tuesday that he still has nightmares about the attack but is unable to identify any of his assailants.

Speaking through an interpreter, Choi Sai-Choi, a bookkeeper who immigrated from Hong Kong four years ago, said he could not identify the people who pulled him from his car at Florence and Normandie avenues--the same intersection where trucker Reginald O. Denny was beaten--April 29, 1992.

He also said he could not identify the people who threw rocks and other objects at his car, those who kicked and beat him or those who took his belongings.

Taking the stand on the third day of testimony in the trial of two men charged with the attempted murder of Denny, Choi said he suffered injuries to his head and lower back before a black off-duty firefighter rescued him. He said he lost his job because he has been unable to work since the attack.

Damian Monroe Williams, 20, and Henry Keith Watson, 29, are charged with assaulting Denny, five other motorists and two firefighters as they passed through the intersection. They are not charged with crimes against Choi, prosecutors said, because their case already was in court when Choi was identified.

"To add those charges would have delayed the preliminary hearing," Deputy Dist. Atty. Lawrence C. Morrison, one of two prosecutors on the case, said outside court. "To add the charges later would have further delayed getting the case to trial."

Superior Court Judge John Ouderkirk reminded jurors before Tuesday's testimony that Williams and Watson were not charged with beating Choi, and they should use the testimony and videotape footage shown only to establish intent or to identify Williams and Watson.

No prosecution witnesses have identified Williams or Watson, but Morrison was confident Tuesday that the jury would be able to readily recognize the defendants when prosecutors complete their case.

"Putting on a case like this is like assembling pieces of a jigsaw puzzle," Morrison said. "The first three or four witnesses are not the complete picture we will present to the jury."

Although prosecutors have not named Williams and Watson as individuals on a videotape of various assaults at Florence and Normandie, they identified the defendants in their opening statement last week by their clothing and other characteristics.

As a result, the defendants have not been referred to by name in testimony, but the man prosecutors say is Williams is repeatedly described as wearing a white T-shirt, dark shorts and a blue bandanna on the videotapes. Another man shown in a white T-shirt and a black cap with a tag on it is Watson, prosecutors say.

On the videotape played in court Tuesday, the man prosecutors say is Watson is shown throwing something at Choi's black Ford Fiesta. A later sequence shows him throwing objects at a red car.

Off-duty Los Angeles Firefighter Donald R. Jones testified Tuesday that he went to Choi's aid, helping him get back into his car as looters were taking his belongings.

"A man at the intersection told me I only had a few more seconds in the intersection," Jones said, adding that the remark made him feel that his life was in danger. But he did not leave Choi, who "appeared confused, hurt and afraid."

"When I walked over to him, he clutched both my legs with his arms and said, 'Thank You,' " said Jones, who is black.

He drove Choi to Fire Station 57 at Vermont Avenue and 79th Street, where he called paramedics who took him to a hospital. As he drove Choi away from Florence and Normandie, Jones said, the crowd started throwing rocks at the car again when they saw Choi inside.

Jones said he could not identify any of the people shown throwing rocks at the intersection, but he said the prosecution videotape portrays the scene he saw there.

In his 30 minutes at the intersection, Jones said, he saw someone in a white T-shirt and dark shorts--clothing prosecutors say identifies Williams--throwing rocks at the intersection.

During earlier testimony, jurors leaned forward in their chairs as they intently watched videotape of an assault on another trucker, Larry Tarvin, who was carrying a load of medical supplies.

Watson is charged with assault with a deadly weapon and robbery of Tarvin, who was pulled from his truck at the intersection and thrown through the air like "a sack of potatoes," prosecutors said.